The present invention relates to a semiconductor laser device manufacturing method as well as a semiconductor laser device.
A conventional semiconductor laser device manufacturing method, as shown in FIG. 13, includes a first inspection step S101, a mounting step S102, a burn-in step or aging step S103, and a second inspection step S104 (see JP 4-184175 A).
At the first inspection step S101, a threshold current value of the semiconductor laser chip is inspected. More specifically, as shown in FIG. 14, a pulse current of 150 mA is passed every 1 ms for 1 μs through the semiconductor laser chip at an atmospheric temperature of room temperature (about 25° C.). Then, as shown in FIG. 15, optical output and current characteristics of the semiconductor laser chip are determined to determine a threshold current Ith and a drive current Iop. Then, the semiconductor laser chip is subjected to a screening by a criterion that if its threshold current Ith and drive current Iop respectively are equal to or lower than specified values, the semiconductor laser chip is decided as a conforming article, and that if its threshold current Ith or drive current Iop exceeds the specified value, the semiconductor laser chip is decided as a nonconforming article.
At the mounting step S102, the semiconductor laser chip that has undergone the first inspection step S101 is mounted onto a package.
At the aging step S103, the mounted semiconductor laser chip is put into conduction at an atmospheric temperature of 70° C., which is not higher than the storage temperature, so that the drive current for the semiconductor laser chip is stabilized. More specifically, as shown in FIG. 16, the drive current Iop is passed through the semiconductor laser chip at the atmospheric temperature of 70° C. so that the optical output of the semiconductor laser chip becomes 100 mW. The vertical axis represents the drive current Iop, and the horizontal axis represents conduction time.
As shown in FIG. 16, the drive current for the semiconductor laser chip increases once after the start of the conduction, and then decreases to approach a certain value. The state that the drive current increases is referred to as a degradation phenomenon, and the state that the drive current decreases is referred to as an upgrade phenomenon.
Thus, in the aging step S103, the semiconductor laser chip, if it does not upgrade but degrade, is removed as a nonconforming article, while the semiconductor laser chip is upgraded to some extent to achieve a stabilization of the drive current for the semiconductor laser chip.
At the second inspection step S104, as in the first inspection step S101, the threshold current Ith and the drive current Iop of the semiconductor laser chip are inspected.
However, with this conventional manufacturing method for semiconductor laser chips, it would take as long a time as about 10 to 20 hours so that the drive current for the semiconductor laser chips is stabilized in the aging step S103.
Also, the aging step (burn-in step) S103 is performed for the first time after the mounting step S102, and the second inspection step S104 is performed thereafter. Therefore, upon incidence of a nonconforming article, not only the semiconductor laser chip but also the package or system or the like would inevitably be discarded. This would cause wasteful component parts to increase, posing such problems as higher cost of the semiconductor laser device and worse yields.
Furthermore, the aging step (burn-in step) S103 subsequent to the mounting step S102 takes about 10 to 20 hours, causing worse throughput. Therefore, the actual case would be that semiconductor laser devices, which have been upgraded to such an extent as to be free from occurrence of considerable problems, are taken as conforming articles and shipped, in consideration of the manufacturing cost.